Secondary lymphedema occurs because of damage or trauma to the lymphatic system. Common causes of lymphatic system damage include: cancer-related surgery, radiation therapy, traumatic injury, or parasitic infection.
Specific cancer-related surgeries, such as those done for tumor removal, require removal of lymph nodes. The removal of lymph nodes reduces the system’s ability to move fluid and puts people at risk of developing swelling. Surgical techniques such as sentinel node biopsy strive to remove fewer nodes, aiming to preserve the lymphatics and reduce risk for swelling. The sentinel node procedure still disrupts the lymphatic system and introduces some risk for developing lymphedema.
Radiation therapy is a standard treatment for many types of cancer. Radiation can damage otherwise healthy lymph nodes and vessels, causing scarring that interrupts the normal flow of the lymphatic fluid and introduces the risk for swelling.
Once the lymphatic system is damaged, secondary lymphedema can develop any time there is undue trauma or injury to the body. Because the lymphatic system is impaired, its ability to absorb and carry fluid is diminished. Therefore, if the system is overloaded with fluid from an injury or infection that causes inflammation, swelling may result.
Traumatic injuries inadvertently or accidentally disrupt lymphatic vessels and may result in lymphatic system impairment and lead to the onset of lymphedema.
Parasitic infections are world-wide the most prevalent cause of damage to the lymphatic system and lead to a form of lymphedema called filariasis. This condition affects people primarily in subtropical areas of Southeast Asia, India, Central America, and Africa. A mosquito bite injects the filarial larvae into the lymphatic system. These larvae mature into adult worms in the lymphatic vessels, causing severe lymphedema.